chrome/browser/chromeos/ui/accessibility_focus_ring_controller.cc

   1 // Copyright 2014 The Chromium Authors. All rights reserved.
   2 // Use of this source code is governed by a BSD-style license that can be
   3 // found in the LICENSE file.
   4
   5 #include "chrome/browser/chromeos/ui/accessibility_focus_ring_controller.h"
   6
   7 #include "ash/display/display_controller.h"
   8 #include "ash/shell.h"
   9 #include "base/logging.h"
  10 #include "chrome/browser/chromeos/ui/focus_ring_layer.h"
  11 #include "ui/gfx/screen.h"
  12
  13 namespace chromeos {
  14
  15 namespace {
  16
  17 // The number of pixels the focus ring is outset from the object it outlines,
  18 // which also determines the border radius of the rounded corners.
  19 // TODO(dmazzoni): take display resolution into account.
  20 const int kAccessibilityFocusRingMargin = 7;
  21
  22 // Time to transition between one location and the next.
  23 const int kTransitionTimeMilliseconds = 300;
  24
  25 // A Region is an unordered collection of Rects that maintains its
  26 // bounding box. Used in the middle of an algorithm that groups
  27 // adjacent and overlapping rects.
  28 struct Region {
  29   explicit Region(gfx::Rect initial_rect) {
  30     bounds = initial_rect;
  31     rects.push_back(initial_rect);
  32   }
  33   gfx::Rect bounds;
  34   std::vector<gfx::Rect> rects;
  35 };
  36
  37 }  // namespace
  38
  39 // static
  40 AccessibilityFocusRingController*
  41     AccessibilityFocusRingController::GetInstance() {
  42   return Singleton<AccessibilityFocusRingController>::get();
  43 }
  44
  45 AccessibilityFocusRingController::AccessibilityFocusRingController()
  46     : compositor_(nullptr) {
  47 }
  48
  49 AccessibilityFocusRingController::~AccessibilityFocusRingController() {
  50 }
  51
  52 void AccessibilityFocusRingController::SetFocusRing(
  53     const std::vector<gfx::Rect>& rects) {
  54   rects_ = rects;
  55   Update();
  56 }
  57
  58 void AccessibilityFocusRingController::Update() {
  59   previous_rings_.swap(rings_);
  60   rings_.clear();
  61   RectsToRings(rects_, &rings_);
  62   layers_.resize(rings_.size());
  63   for (size_t i = 0; i < rings_.size(); ++i) {
  64     if (!layers_[i])
  65       layers_[i] = new AccessibilityFocusRingLayer(this);
  66
  67     if (i > 0) {
  68       // Focus rings other than the first one don't animate.
  69       layers_[i]->Set(rings_[i]);
  70       continue;
  71     }
  72
  73     gfx::Rect bounds = rings_[0].GetBounds();
  74     gfx::Display display =
  75       gfx::Screen::GetNativeScreen()->GetDisplayMatching(bounds);
  76     aura::Window* root_window = ash::Shell::GetInstance()->display_controller()
  77         ->GetRootWindowForDisplayId(display.id());
  78     ui::Compositor* compositor = root_window->layer()->GetCompositor();
  79     if (!compositor || root_window != layers_[0]->root_window()) {
  80       layers_[0]->Set(rings_[0]);
  81       if (compositor_ && compositor_->HasAnimationObserver(this)) {
  82         compositor_->RemoveAnimationObserver(this);
  83         compositor_ = nullptr;
  84       }
  85       continue;
  86     }
  87
  88     focus_change_time_ = base::TimeTicks::Now();
  89     if (!compositor->HasAnimationObserver(this)) {
  90       compositor_ = compositor;
  91       compositor_->AddAnimationObserver(this);
  92     }
  93   }
  94 }
  95
  96 void AccessibilityFocusRingController::RectsToRings(
  97     const std::vector<gfx::Rect>& src_rects,
  98     std::vector<AccessibilityFocusRing>* rings) const {
  99   if (src_rects.empty())
 100     return;
 101
 102   // Give all of the rects a margin.
 103   std::vector<gfx::Rect> rects;
 104   rects.resize(src_rects.size());
 105   for (size_t i = 0; i < src_rects.size(); ++i) {
 106     rects[i] = src_rects[i];
 107     rects[i].Inset(-GetMargin(), -GetMargin());
 108   }
 109
 110   // Split the rects into contiguous regions.
 111   std::vector<Region> regions;
 112   regions.push_back(Region(rects[0]));
 113   for (size_t i = 1; i < rects.size(); ++i) {
 114     bool found = false;
 115     for (size_t j = 0; j < regions.size(); ++j) {
 116       if (Intersects(rects[i], regions[j].bounds)) {
 117         regions[j].rects.push_back(rects[i]);
 118         regions[j].bounds.Union(rects[i]);
 119         found = true;
 120       }
 121     }
 122     if (!found) {
 123       regions.push_back(Region(rects[i]));
 124     }
 125   }
 126
 127   // Keep merging regions that intersect.
 128   // TODO(dmazzoni): reduce the worst-case complexity! This appears like
 129   // it could be O(n^3), make sure it's not in practice.
 130   bool merged;
 131   do {
 132     merged = false;
 133     for (size_t i = 0; i < regions.size() - 1 && !merged; ++i) {
 134       for (size_t j = i + 1; j < regions.size() && !merged; ++j) {
 135         if (Intersects(regions[i].bounds, regions[j].bounds)) {
 136           regions[i].rects.insert(regions[i].rects.end(),
 137                                   regions[j].rects.begin(),
 138                                   regions[j].rects.end());
 139           regions[i].bounds.Union(regions[j].bounds);
 140           regions.erase(regions.begin() + j);
 141           merged = true;
 142         }
 143       }
 144     }
 145   } while (merged);
 146
 147   for (size_t i = 0; i < regions.size(); ++i) {
 148     std::sort(regions[i].rects.begin(), regions[i].rects.end());
 149     rings->push_back(RingFromSortedRects(regions[i].rects));
 150   }
 151 }
 152
 153 int AccessibilityFocusRingController::GetMargin() const {
 154   return kAccessibilityFocusRingMargin;
 155 }
 156
 157 // Given a vector of rects that all overlap, already sorted from top to bottom
 158 // and left to right, split them into three shapes covering the top, middle,
 159 // and bottom of a "paragraph shape".
 160 //
 161 // Input:
 162 //
 163 //                       +---+---+
 164 //                       | 1 | 2 |
 165 // +---------------------+---+---+
 166 // |             3               |
 167 // +--------+---------------+----+
 168 // |    4   |         5     |
 169 // +--------+---------------+--+
 170 // |             6             |
 171 // +---------+-----------------+
 172 // |    7    |
 173 // +---------+
 174 //
 175 // Output:
 176 //
 177 //                       +-------+
 178 //                       |  Top  |
 179 // +---------------------+-------+
 180 // |                             |
 181 // |                             |
 182 // |           Middle            |
 183 // |                             |
 184 // |                             |
 185 // +---------+-------------------+
 186 // | Bottom  |
 187 // +---------+
 188 //
 189 // When there's no clear "top" or "bottom" segment, split the overall rect
 190 // evenly so that some of the area still fits into the "top" and "bottom"
 191 // segments.
 192 void AccessibilityFocusRingController::SplitIntoParagraphShape(
 193     const std::vector<gfx::Rect>& rects,
 194     gfx::Rect* top,
 195     gfx::Rect* middle,
 196     gfx::Rect* bottom) const {
 197   size_t n = rects.size();
 198
 199   // Figure out how many rects belong in the top portion.
 200   gfx::Rect top_rect = rects[0];
 201   int top_middle = (top_rect.y() + top_rect.bottom()) / 2;
 202   size_t top_count = 1;
 203   while (top_count < n && rects[top_count].y() < top_middle) {
 204     top_rect.Union(rects[top_count]);
 205     top_middle = (top_rect.y() + top_rect.bottom()) / 2;
 206     top_count++;
 207   }
 208
 209   // Figure out how many rects belong in the bottom portion.
 210   gfx::Rect bottom_rect = rects[n - 1];
 211   int bottom_middle = (bottom_rect.y() + bottom_rect.bottom()) / 2;
 212   size_t bottom_count = std::min(static_cast<size_t>(1), n - top_count);
 213   while (bottom_count + top_count < n &&
 214          rects[n - bottom_count - 1].bottom() > bottom_middle) {
 215     bottom_rect.Union(rects[n - bottom_count - 1]);
 216     bottom_middle = (bottom_rect.y() + bottom_rect.bottom()) / 2;
 217     bottom_count++;
 218   }
 219
 220   // Whatever's left goes to the middle rect, but if there's no middle or
 221   // bottom rect, split the existing rects evenly to make one.
 222   gfx::Rect middle_rect;
 223   if (top_count + bottom_count < n) {
 224     middle_rect = rects[top_count];
 225     for (size_t i = top_count + 1; i < n - bottom_count; i++)
 226       middle_rect.Union(rects[i]);
 227   } else if (bottom_count > 0) {
 228     gfx::Rect enclosing_rect = top_rect;
 229     enclosing_rect.Union(bottom_rect);
 230     int middle_top = (top_rect.y() + top_rect.bottom() * 2) / 3;
 231     int middle_bottom = (bottom_rect.y() * 2 + bottom_rect.bottom()) / 3;
 232     top_rect.set_height(middle_top - top_rect.y());
 233     bottom_rect.set_height(bottom_rect.bottom() - middle_bottom);
 234     bottom_rect.set_y(middle_bottom);
 235     middle_rect = gfx::Rect(enclosing_rect.x(), middle_top,
 236                             enclosing_rect.width(), middle_bottom - middle_top);
 237   } else {
 238     int middle_top = (top_rect.y() * 2 + top_rect.bottom()) / 3;
 239     int middle_bottom = (top_rect.y() + top_rect.bottom() * 2) / 3;
 240     middle_rect = gfx::Rect(top_rect.x(), middle_top,
 241                             top_rect.width(), middle_bottom - middle_top);
 242     bottom_rect = gfx::Rect(
 243         top_rect.x(), middle_bottom,
 244         top_rect.width(), top_rect.bottom() - middle_bottom);
 245     top_rect.set_height(middle_top - top_rect.y());
 246   }
 247
 248   if (middle_rect.y() > top_rect.bottom()) {
 249     middle_rect.set_height(
 250         middle_rect.height() + middle_rect.y() - top_rect.bottom());
 251     middle_rect.set_y(top_rect.bottom());
 252   }
 253
 254   if (middle_rect.bottom() < bottom_rect.y()) {
 255     middle_rect.set_height(bottom_rect.y() - middle_rect.y());
 256   }
 257
 258   *top = top_rect;
 259   *middle = middle_rect;
 260   *bottom = bottom_rect;
 261 }
 262
 263 AccessibilityFocusRing AccessibilityFocusRingController::RingFromSortedRects(
 264     const std::vector<gfx::Rect>& rects) const {
 265   if (rects.size() == 1)
 266     return AccessibilityFocusRing::CreateWithRect(rects[0], GetMargin());
 267
 268   gfx::Rect top;
 269   gfx::Rect middle;
 270   gfx::Rect bottom;
 271   SplitIntoParagraphShape(rects, &top, &middle, &bottom);
 272
 273   return AccessibilityFocusRing::CreateWithParagraphShape(
 274       top, middle, bottom, GetMargin());
 275 }
 276
 277 bool AccessibilityFocusRingController::Intersects(
 278   const gfx::Rect& r1, const gfx::Rect& r2) const {
 279   int slop = GetMargin();
 280   return (r2.x() <= r1.right() + slop &&
 281           r2.right() >= r1.x() - slop &&
 282           r2.y() <= r1.bottom() + slop &&
 283           r2.bottom() >= r1.y() - slop);
 284 }
 285
 286 void AccessibilityFocusRingController::OnDeviceScaleFactorChanged() {
 287   Update();
 288 }
 289
 290 void AccessibilityFocusRingController::OnAnimationStep(
 291     base::TimeTicks timestamp) {
 292   if (rings_.empty())
 293     return;
 294
 295   CHECK(compositor_);
 296   CHECK(!rings_.empty());
 297   CHECK(!layers_.empty());
 298   CHECK(layers_[0]);
 299
 300   // It's quite possible for the first 1 or 2 animation frames to be
 301   // for a timestamp that's earlier than the time we received the
 302   // focus change, so we just treat those as a delta of zero.
 303   if (timestamp < focus_change_time_)
 304     timestamp = focus_change_time_;
 305
 306   base::TimeDelta delta = timestamp - focus_change_time_;
 307   base::TimeDelta transition_time =
 308       base::TimeDelta::FromMilliseconds(kTransitionTimeMilliseconds);
 309   if (delta >= transition_time) {
 310     layers_[0]->Set(rings_[0]);
 311     compositor_->RemoveAnimationObserver(this);
 312     compositor_ = nullptr;
 313     return;
 314   }
 315
 316   double fraction = delta.InSecondsF() / transition_time.InSecondsF();
 317
 318   // Ease-in effect.
 319   fraction = pow(fraction, 0.3);
 320
 321   layers_[0]->Set(AccessibilityFocusRing::Interpolate(
 322       previous_rings_[0], rings_[0], fraction));
 323 }
 324
 325 void AccessibilityFocusRingController::OnCompositingShuttingDown(
 326     ui::Compositor* compositor) {
 327   DCHECK_EQ(compositor_, compositor);
 328   compositor_->RemoveAnimationObserver(this);
 329   compositor_ = nullptr;
 330 }
 331
 332 }  // namespace chromeos